I'm about to update my toolkit, and thought this would be a good topic to start a discussion and see what everyone else does:

Excluding a laptop/smartphone, what do you consider the most essential tools someone would need while working out in the field?

I personally like to keep a "doctor's bag" at the ready by the door, so whenever something goes on I can grab it and head out on call. If I know I'll be working on a certain project at work, I just grab my toolbox and head out the door. If Mom needs my help, I'm on my way to save the day (in exchange for a free home-cooked meal). Since I'm also a Ghost Hunter, I can grab this quickly if I'm called up for an investigation, using my tools to set up base camp just as easily as something at the office or the off-site datacenter for work.

Even when I'm geeking at home, things are conveniently stored in a neatly-organized place, everything in their own little pouch where it's easy to find. I can't stress the importance of that last one enough...most techs, left to their own devices for long enough, will have things scattered out all over the place like a mad scientist's laboratory. You know it's true.

Anyone else do the same, either for your personal toys or for "on call" kits for some of the employees you might manage? What do you consider to be the essentials that you wouldn't leave home without?

Some of these are going to be basic...things like a spare patch cable or a screwdriver. But it's curious to see how many go through the trouble of keeping a kit and how many don't, and when you're optimizing for size and weight, what items make the cut and what all gets left behind.

I'm not in the field as much as I used to be, but there's still one thing I carry around every day: my Gerber multitool. I've had it for the last 11-12 years and I love it. It's becoming a little old though, so I'm looking to buy a new one.

As far as what's inside my laptop bag that I would put into a toolkit if it still had one:

Some type of VOM meter for checking voltages, continuity, etc. Console cable, spare cat5/cat6 cables, my Compaq multi screwdriver with various bits. Small side cutters. USB or external drive with utilities and potential save the day software.

I usually carry the electrician's pouch inside the large toolbag. I can remove it anytime I just want to carry those tools. I take the bag and backpack everywhere. If I have a PC or other equipment, I also take the flat cart to put it all on. It folds up and fits in a truck. Being a one-man operation, I have to do a lot different things so I need to be well-equiped.

Totally with you C Thompson. I did structure cabling before I took over as Sys Admin so I have a tool bag with basically any necessity tool you need. I could put together a server room with rack and ladder tray and then work on your computers.

DBAN, Memtest, Offline NT Password & Registry Editor, Ultimate Boot CD, Ubuntu 10.10, Parted Magic, and a few others. I also keep a few tools on the key, like Sysinternals, Combofix, ccleaner, etc...

I only carry CDs with older machines that can't boot from USB. Thankfully, there are fewer of those these days.

When I was doing more hardware swaps, I had a simple ratchetting screwdriver. Now I just use the leatherman. I also keep a patch cable or two in my bag, along with the laptop and a USB cable for my phone (PDANet for internet access if the local net is down). Oh, and a snack bar.

Oh yeah, and what I use almost every day is my USB Flash drive with all the Microsoft service packs for Windows and Office and free software that I put on all computers such as the latest versions Chrome, flash, java, dopdf, etc.